Bath Time Love Time
by Anonymonimus
Summary: US Sans opts for a cold bath when his heat gets out of hand. UNDERSWAP


**Eyyy! Here we are again folks! Another addition to the Bath Time Fun Time series!**

 **So far, people have been asking me for SwapFell, King Papyrus AU, and Underlust. I might be missing one which means I'll have to skim through the comments of last chapter to compile a complete list.**

 **I think the next one I'm doing is SwapFell or Underlust anyway.**

 **On that note, I feel like I exhausted the whole "heat" thing, so I'm going to switch it to something else for the next three and so forth.**

 **ENJOY!**

* * *

The magnificent Sans was in a less than magnificent situation. It was that time of the month again: his heat. Where he wouldn't have initially minded what with having Papyrus around to help, he was far from thrilled this time around what with Alphys's assessment test coming up. Tomorrow, he would be once again attempting to prove himself to the Captain of the Queen's Guard and he really felt like things were going to go his way this time. This had him stuck in a tricky position. If he gave in to the heat and had sex with Papyrus until it passed, he would be sore the next day and wouldn't perform to the best of his ability. Conversely, if he ignored it, the heat would last for two extra days before finally passing which could mean a possible distraction during his test.

There wasn't a clear win in this situation. However, after a long moment of deliberation, Sans opted for the second solution: he would ignore his heat. He rationalised that a mental distraction was easier to handle than a physical impairment. Alphys might even be impressed by the strength of his resolve if he managed to pass her test. The simple thought quickly had Sans imagining Alphys praising him which cemented his decision. He was going to impress her so much; it was definitely going to be amazing!

"Hey bro." Papyrus greeted as he walked into the kitchen. He wore a black tank top rather than his typical orange sweater. That in itself probably meant he had dirtied it and placed it in the laundry basket for Sans to wash. Unfortunately, the form fitting piece of clothing did nothing to help the smaller skeleton with his heat.

"dirtied your sweater again, did you?" Sans noted tensely. It was okay. This was fine. Sans had a great mental resolve! He could get through this.

"Yeah. Bottle of honey was screwed in weirdly." Papyrus explained as he took a seat at the table. "It got all over me. Muffet laughed. A lot."

"you really shouldn't drink it straight like that." Sans chastised all the while he tried not lewdly imagining his brother covered in honey. "it's not healthy."

"I've got to treat myself once in a while." Papyrus chuckled. "Speaking of 'healthy', are you going to make some tacos or what?"

"yes, yes." Sans sighed throwing his hands up, "i was _just_ getting to that when you distracted me."

Papyrus laughed again, "Right." He said, evidently amused.

Without a further word, Sans got to work. He gathered the ingredients from the fridge and lined them up on the kitchen counter. He pushed the lettuce, tomatoes and onions to one side, the cheese and hashed meat to another, and kept the sour cream and salsa next to the taco shells. He then reached for the cutting board and vegetable knife, halting momentarily when he felt Papyrus's gaze barring into his back. Hesitantly, the smaller skeleton peaked over his shoulder and found his brother staring at him with a small orange blush dusting his cheeks. He didn't seem to notice he had been caught – that or he didn't care.

Sans glanced away and forced himself to start cutting up the ingredients. He would use fire magic to cook the meat so there was no point in turning on the stove. While he did so, his mind strayed: wondering if Papyrus had picked up on his heat. Sans thought against it. There was no way. Papyrus would have mentioned it, right…?

"Smells really nice, bro." Papyrus commented abruptly which made Sans jolt in surprise.

"e-erm…" he stammered, looking down at the onion he was chopping. A part of Sans suspected Papyrus wasn't remotely referring the vegetable in question. "…thank…you?"

Sans shook the comment off and forced himself not to think further of it. The last thing he wanted was to start indulging in perverted fantasies that would do nothing for his heat. He didn't want to imagine Papyrus getting up from the table, shoving the ingredients on the counter aside to prop him up on the surface and fuck him savagely—

 _no! stop it!_ Sans chastised to himself. However the mental imagery had affected his heat enough to have him conjure an ecto vagina. He tried to will it away but to no avail. _this is…not good…_

Suddenly, Papyrus rose from his seat. The chair scrapped against the kitchen floor, startling Sans out of his thoughts. He turned back agitatedly, his heart beating madly in his chest. "Need help there?" Papyrus asked. And maybe it was Sans's imagination but he could have sworn he had purred. Was he aware of his heat? Was it affecting him?

"y-you know what?" Sans stuttered nervously. "there are tacos already in the fridge. we'll just eat those. i-i…um…need to take a…a bath."

And before Papyrus could ask why the sudden change of heart, Sans ran past him and upstairs. He leaned against the bathroom door once he shut it behind him and sighed deeply. Controlling his heat through sheer willpower was not going well at all. Not even the thought of impressing Alphys if he passed was able to get him back on track. He stared at the ceiling in exasperation before dropping his gaze downwards. He caught sight of the bathtub. Maybe a cold, cold, _cold_ bath would help.

 _it certainly wouldn't hurt_ , Sans thought as he began stripping. His heat was making him feel, well, hot.

He made his way to the tub and turned on the cold water, waiting for it to fill three quarters of it before jumping in. He squealed in discomfort and felt chills crawl through his bones. It thankfully subsided after a few long minutes and Sans was capable of relaxing a bit. He stretched out his legs and leaned against one end, sinking slightly further into the water. The cold was helping calm down his raging desires though they were still very much present. But as long as the skeleton could control them, he would be fine—

"Hey, Sans…?" Papyrus asked, startling Sans again. _oh no._ The taller skeleton was just on the other side of the door. He slowly began pushing in as he continued with: "Are you mad at me…?"

"s-stop!" Sans exclaimed anxiously. Papyrus effectively halted behind the door. "i…don't worry. i'm not mad at you…i just need to focus for tomorrow…"

"But why does focusing mean casting me aside like this?" Papyrus asked, pushing the door the rest of the way as he stepped in.

Sans squeaked and ducked in the tub, dragging his knees to his chest and attempting to cover himself with his arms. Obviously, it wasn't working but it was the thought that counted. Papyrus gave him a bizarre look.

"Sans?" He repeated as he strayed closer, "What's going on?"

"nothing…" Sans insisted, ignoring the ecto vagina between his legs.

Papyrus gave him a look which suggested he didn't believe him. But then his look of suspicion disappeared and before Sans knew it, the taller skeleton was stripping. He blushed heavily and stammered stupidly as he tried to form words. "pa-papyrus! what are you doing!?" he squeaked.

"I'm getting in the bath with you." Papyrus replied nonchalantly, throwing his black tank top aside and unbuttoning his baggy pants. "Don't act all coy, Sans. We've seen each other naked a lot of times."

"b-but why…?" Sans tried. He didn't want a naked Papyrus around him when he was trying so hard to resist his heat. He didn't know if he could resist his urges in the unfolding scenario.

"Well, we have sex and you've got to be a little naked to—"

"that's not what i meant and you know it!" Sans interrupted abruptly. Papyrus laughed.

"If you're really not angry with me," the taller skeleton said, "Then you won't mind me bathing with you. It's been a while since the last time."

"i-i'm not angry with you…" Sans repeated, casting his glance aside. He didn't know how to make his brother understand that he needed space given his heat. "the water's just…really cold. you wouldn't enjoy yourself…"

Papyrus rolled his eyes and snorted. He dropped his pants and jumped in the tub without a second thought. Water splashed, hitting Sans in the face and flooding the bathroom floor. The smaller skeleton scowled, unhappy with having to clean a mess of water later, though not for long as Papyrus began flailing and shouting.

"Holy shit this is fucking cold!" He cried, immediately pushing himself back out with only his feet in the water, "How can you just sit in there like that!?"

"don't swear, papyrus." Sans chastised. "and i wanted a cold bath."

"Why?" Papyrus asked, still refusing to sink back into the water. Unfortunately, that meant Sans had a very nice view of his naked body. His pelvis tingled with excitement and desire. The cold water was losing its effect. "Seriously, Sans, you could get sick—"

"gah! i'm having a heat, okay!?" the smaller skeleton finally snapped. He couldn't hold his tongue anymore. Not when Papyrus was being all naked in front of him.

"Why are you acting like that's a bad thing?" Papyrus asked.

"because," Sans sighed, burying his face in his knees, "i have alphys's assessment test tomorrow and if we have sex i won't be up to par…i'll be sore…"

"Well…" Papyrus muttered, blushing at the insinuated comment, "I can just be gentle…"

Sans supposed that was an option – or it would have been much earlier. Now, he was caving into his horniness. The assessment test be damned, he could ask Alphys to push it back or something; anything. There were more pressing matters like being fucked until Sans screamed himself hoarse. Just the thought being fucked roughly had him moaning quietly in his given state. He couldn't do it. He didn't have the resolve to repress his heat until after his assessment test tomorrow.

"no…" Sans replied, looking straight at Papyrus, "i don't want that. i want you to fuck me hard like you usually do. i want you to make me scream until i can't anymore."

Papyrus blushed and grinned. He finally lowered himself back into the water as Sans opened his legs. "I love it when you talk dirty, Sansy…" he purred, inching closer.

Sans's breath hitched as Papyrus's hands travelled up his femur and wasted little to no time reaching his ecto vagina. He immediately pushed two fingers in, thrusting slowly and teasingly. Where Sans would have once allowed him to continue his ministrations patiently, he refused to do so this time around. He wanted to be fucked. Screw the foreplay, he wanted Papyrus's dick inside of him now.

"papy just fuck me." Sans whined, reaching for Papyrus's pelvis. The latter gasped and moaned lightly as the sensitive bone was massaged, encouraging him to use his sexual magic to conjure an ecto cock. "i want your penis inside me…i don't want to wait…"

Papyrus leaned in, kissing Sans gently. "I was never able to refuse you anything." he chuckled.

He then conjured the cock the smaller skeleton was demanding so lewdly. Sans blushed at the sight of it, the need to be penetrating increasing tenfold. He whined, wiggling his hips invitingly. Papyrus smirked and brought the tip of his organ to the offered entrance. He glanced up quickly, requesting Sans's silent permission before pushing in.

The small skeleton threw his head back and cried out. Papyrus's cock always felt so good inside him. It plowed him so relentlessly, so perfectly, that it drained any and all of his abilities to think. All Sans could do was hold on to Papyrus as he cried out his name and begged for more. Bliss washed over his body, it filled his bones and had his heart thumping madly in his ribcage. How could he care about the mess of water on the floor or the assessment test he would surely fail tomorrow when he felt so good in the moment?

"You like it when I fuck you like this, Sans?" Papyrus groaned as he snapped his hips harshly.

"yes! stars yes, _papyrus_!" Sans cried out, vainly attempting to move in time with the unyielding thrusts. "ahh! it feels so – _mmf_ – good! you make me feel so good, papy!"

Papyrus shifted their position abruptly. He lifted Sans slightly, gaining better access to thrust deeper into him. The moment his cock pushed in further than it did before, a lecherous, _dirty_ moan escaped his mouth as tears prickled his eyes. The pleasure was so intense, so good that Sans felt like he was starting to go mad. He absolutely needed to cum, but he never wanted it to end. If it meant going insane, then, honestly, so be it. However, it was not the case. Several powerful thrusts later, Sans was crying out as an orgasm shook his body hard and drained him of most of his energy. Papyrus made quick work of finishing himself off soon after.

With both having reached their climax, they stopped for a moment to catch their breaths. Sans's body was trembling a bit from the aftershocks of such a powerful release. Papyrus seemed thoroughly amused by that. He chuckled and pressed a soft kiss on the top of the smaller skeleton's skull.

"Sorry for messing up your chances for your assessment test." He apologised somewhat genuinely.

"that's honestly the furthest thing from my mind right now." Sans admitted, then nuzzling his head in the crook of his brother's neck, "all i want is to go at it again…"

"Sure." Papyrus agreed with a careless shrug, "As long as we change places. This water's cold as hell."


End file.
